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This article was first published in 2007.
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In
August 2006 JCB and Ricardo succeeded in breaking the world land speed record
for diesel cars – in a vehicle powered by engines originally designed by the two
companies for back-hoe loaders! We report on the 19 months of intensive and
inspired development work that produced the world’s highest specific power
automotive diesel engines and, finally, international glory. This article was
first published in Ricardo Quarterly Review and is used with permission.
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It is mid-morning on 23rd August 2006 and
Ricardo’s Matt Beasley, in common with his team of diesel engineers, feels a
sense of sheer elation. Together with colleagues at Ricardo and JCB, they had
successfully completed a remarkable engineering program that had transformed the
existing, co-developed JCB444 engine from a sturdy construction equipment unit
into the world’s highest specific power automotive diesel – the JCB444-LSR. It
was with this engine that the JCB Dieselmax had just broken the Bonneville
SpeedWeek record for a diesel car and set two new FIA certified international
land speed records in the space of just six days.
The JCB Dieselmax roared from the drawing board
into the history books in a mere 19 months, setting the Bonneville record of
317.021 mph and a new land speed record for diesel cars of 350.092 mph (563.418
km/h). But if the idea of a diesel-powered record breaker was unusual enough,
the notion of using the engines from a back-hoe loader – a class of vehicle not
usually noted for its speed – for the 350 mph bid appeared extraordinary.
JCB group engineering director Tim Leverton
recalls how the diesel record breaker concept was born. “The idea came from Sir
Anthony Bamford and was prompted by the decision to go ahead with production of
the JCB444 engine. He thought it was an excellent way of promoting the fact that
we had entered the engine business and would also fulfil a long-held dream to
embark upon a land speed record project.”
Ricardo had been a natural choice of partner on
the JCB444-LSR speed record development program. The company had been powertrain
partner on the original JCB444, taking lead responsibility for the original
concept development and then gradually handing over responsibility to JCB
engineers as the program progressed. It was as part of this program that Sir
Anthony Bamford had visited the Ricardo Shoreham Technical Centre and had the
inspiration for the audacious landspeed record bid on seeing the first JCB444
prototype being tested.
Just two months later, on January 14th 2005,
Ricardo’s global diesel director, Ian Penny, joined the first land speed record
project meeting at Millennium Point in Birmingham (home of John Cobb’s Railton
Mobil Special).The project was shrouded in secrecy and aptly codenamed ‘H-1’
after Howard Hughes’ 350 mph record breaking aircraft of 1935. On Penny’s return
to base Matt Beasley was appointed chief project engineer.
”The start point from our perspective as engine
development partner was to ascertain the approximate power requirement for the
vehicle,” recalls Penny. “JCB wanted to exceed the existing record by a large
margin, so the team established the target of 350 mph. Knowing the altitude of
Bonneville Salt Flats, the range of possible salt conditions and the likely
vehicle drag, we calculated we needed to aim for somewhere in the region of 1500
bhp. With out knowledge of high performance diesel combustion systems from
competition applications and our in-depth experience of the original JCB444
design, we were confident that we could deliver this target from two units based
on a highly developed version of this engine.”
Towards 1500 Horsepower
Work began on the simulation using the Ricardo
WAVE software. “Once we had the scope,” explains Beasley, “we could decide which
engine components could be carried over and which should be bespoke.” The value
of Ricardo’s previous role in the design of the JCB444 engine really came into
its own at this stage. “The fact that we had validated CAE models of almost
every aspect of the baseline engine enabled us to make rapid progress”,
continues Beasley. “We could very quickly predict the durability of components
and systems at far higher ratings, safe in the knowledge that the models were of
high fidelity and able to provide reliable data.” The feasibility study would
take until the end of February 2005, Ricardo’s vehicle division coming up with a
basic layout for the car. The favourite was to seat the driver between the two
engines and transmissions – but at that point the first sign of a problem came
into view. In this configuration the frontal area would be too great, weight
would be too high and stability poor.
“I suggested we incline the engines,” says Penny,
“which meant a lot of extra work but it really was the only solution.” It would
also require some complex engineering. “The engine’s lubrication system is
designed to drain vertically and, if inclined, would function best fitted ‘cold
side’ down. However, in order to fit them low enough in the vehicle, the engines
needed to go in ‘hot side’ down.” The team calculated that the best compromise
between natural drainage and vertical height was to incline the engines at 10
degrees from the horizontal. To achieve that, the engines would need a bespoke
dry sump system.
Ricardo calculated that for the speed record
attempt, the two engines would require an intake airflow of almost five tonnes
per hour. More challengingly still, this would need to be delivered at the 1300m
altitude of the Bonneville Salt Flats, where ambient air pressure is 85 per cent
of that at sea level. While the production engine requires a boost pressure of 2
bar, the two engines installed in Dieselmax require 6 bar absolute at full
power. This compares with around 3 bar absolute for a diesel Le Mans racer, and
around 4 bar for the turbo-era Formula 1 cars.
Two-Stage Turbo Boost
“The scale of the air-handling challenge was such
that we realised we needed to go for two-stage turbocharging,” explains Penny.
“Through simulation we were able to show that with both inter-stage and
after-cooling, and with water injection to provide even further charge-cooling
as well as reducing the thermal load on pistons and valves, we could deliver the
required airflow across the engine speed range even at the high altitude of
Bonneville.”
The high boost pressures required for the
JCB444-LSR engines also had an impact on the design of the dry sump system.
While these may be considered conventional for applications such as Le Mans
cars, the Ricardo team realised that such systems would not function under such
extreme boost and thermal loading, as the oil and gas flow rates would need to
be around three times that of competition engines. Beasley explains: “The
combination of high boost levels, increased engine speed and piston cooling jet
oil flow turns the oil into foam, causing it to become highly compressible and
hence risking catastrophic failure within seconds. The oil looks like a pint of
Guinness that has been poured very badly.”
The dry sump tank was carefully designed to
condition the foaming lubricant, incorporating centrifuge separators and baffles
through which the oil flows, in order to remove the air from it. It would take
five layers to achieve a satisfactory result, but the bottom layer would consist
of pure, air-free oil.
If the engine is the heart of the vehicle, then
the combustion system is very much the heart of the engine, and the JCB444-LSR
engines were from the outset designed using Ricardo’s High Speed Diesel Race
(HSDR) direct-injection combustion technology. Fuel is delivered via two
parallel high-pressure pumps to a common-rail system providing an injection
pressure of 1600 bar. Modifications had to be made to the cylinder head to
facilitate the larger injectors required for the HSDR system. Despite these
changes, however, the team decided that the valve train could be carried over
substantially in its original form, with the exception of high-temperature
specification exhaust valves, up-rated valve springs and a modified camshaft
profile.
Combustion Chamber Design
A completely redesigned piston is used with a
large, quiescent combustion chamber that has a reduced overall compression ratio
and specific features to reduce the risk of thermal damage to the combustion
chamber components. Piston cooling was improved over the baseline design by
increasing the cooling oil flow to each piston by around 600 per cent. A
completely new, fully machined connecting rod was used, including a
significantly enlarged small-end bearing to increase strength and robustness.
While giving a longer stroke, the billet-machined crankshaft retains the
production main and big-end bearing sizes and bearing shells.
By now, the team was well into the concept
validation process scheduled to run from March to August, and by July it had the
specification for the first engine mule. Following an exploratory visit to
Bonneville for the 2005 Speed Week, the streamliner’s design had been refined,
becoming even narrower; the track and wheelbase were modified too. Finding
suitable tyres proved a major challenge. Land speed record tyres are available
off-the-shelf, but the manufacturers only provide a 300 mph speed rating. To
make an informed decision as to their suitability to run a 2700 kg car at over
300 mph, the team required validation at target load rating and running
pressure. In the end, JCB located a suitable high speed tyre rig and
independently validated the tyres to 350 mph, the maximum speed of the rig.
First Engine Firing
Final approval for the project was provided in
September 2005, but in view of the three month lead time for the procurement of
parts there was considerable pressure to get an engine running. Given the high
power rating, it had already been decided that the engine required a solid
billet crankshaft, a component which would inevitably require a long lead time.
Luckily, Greville Sharman, Ricardo chief designer on the original JCB444
program, remembered that one of the very first development prototypes of the
JCB444 engine had been produced with just such a crankshaft and was on display
at JCB headquarters. Swiftly requisitioned by the Dieselmax team, it was rushed
to Ricardo and stripped, allowing Matt Beasley’s team to run the first engine
test on October 18th at 10 am.
The engine was initially run vertically installed,
with the original wet sump; no attempt was made at this stage to produce any
serious power figures. Capacity had been increased from 4.4 litres to 4.8 litres
and, by November, the unit was producing 680 bhp against the target of 750 bhp.
Understandably, the mood within the Ricardo team was buoyant. “We were limited
by the common rail fuel pumps available at the time,” recalls Beasley. “These
had lower capacity than those intended for the final build, but the results gave
us great confidence.”
“You have to understand,” adds Penny, “that this
is a bespoke fuel system and there is nothing like it anywhere in the world.
Fitted with a conventional common rail system, an engine like this would produce
no more than 300 bhp. In layman’s terms, this one has very large holes through
which the fuel travels, so controlling the flow is very difficult.”
From February through to May 2006, with the record
attempt looming in August, a significant development effort went into refining
the design of the near-horizontally installed, dry sump version of the
JCB444-LSR land speed record engine. When pushing the limits of performance into
territory that no other engine developer has ever previously explored, some
component failures are to be expected and are an inevitable part of the learning
and development process, enabling subsequent prototypes to achieve better
durability and greater performance. By May the fuel system was further developed
and the first stage engine configuration frozen at 600 bhp. It was this
specification that would ultimately run in the early vehicle tests and take the
Bonneville speed record. By the end of June, both of the 600 bhp Bonneville
speed record engines were complete and ready for installation in the vehicle.
Shakedown Testing Begins
Now ready and fitted with the 600 bhp units, the
car was dispatched to RAF Wittering airbase along with half the engine team, the
other half remaining to continue engine building. Four weeks’ UK vehicle testing
had been planned, but the enormous challenge presented by raising the power
output of the JCB444-LSR engines by 600 per cent and building a bespoke
streamliner vehicle had nibbled away at the schedule, leaving the Dieselmax team
with just 14 days to complete the task. Furthermore, the test criteria were
tough: reaching 200 mph on the 1.7 mile course, a speed equivalent to the
world’s fastest roadgoing supercars.
Inevitably these first shakedown tests brought
with them some serious challenges. The synchronised transmission shifting
systems decided not to co-operate with one another and triggered engine
shutdown, while the ice-based cooling system needed fine tuning. But the biggest
challenge of all came when both water and oil were discovered in the exhaust.
Beasley sums up the seriousness of the dilemma in a mastery of understatement,
remarking, “normally, this is a very bad thing for the engine.”
Despite pressure to change the engine, Beasley
resisted; the amount of work would have been too great. Instead, the team spent
a day and night investigating and eventually discovered a failed injector seal
and a water injection system malfunction. Diesel injectors are precision
components normally assembled in near-surgical conditions, but this option was
not open to Beasley. Instead he decided to strip and reassemble the injector in
situ, working in a tent on the airfield, at two in the morning. It may have been
unconventional but it worked, and the Wittering tests not only yielded a maximum
speed of 201 mph but the engine team was also able to sign off all of the 60
items they had been monitoring. Some boost lag had been evident but not
critical.
In parallel with the Wittering tests, part of the
team continued to work at Ricardo on the development of the final specification
of the engines. On July 17 the announcement was made that the 750 bhp power
target had been achieved and attention was turned to the preparation of the two
FIA-sealed engines which would be fitted to the vehicle for the international
speed record attempt. By the end of July the land speed record engines were
complete, having been sealed by the FIA following verification of the bore and
stroke.
The Legendary Bonneville Salt Flats
The team, plus the car, arrived at Wendover
airfield near Utah’s Bonneville Salt Flats on the Sunday. The team had planned
to use Speed Week as a final test of the vehicle specification before attempting
to take the international record one week later. A comprehensive risk analysis
of the car and engines was used to determine the approach to be taken throughout
this period so that the final development time at Bonneville – the only place
that the vehicle could ultimately be tested in the environment of the record
attempt – could be used to best effect.
By the Thursday before the start of Speed Week the
team had reassembled the car, made the first shakedown runs and noticed an
increase in turbo lag due to the high altitude. The first run on the salt on
Saturday afternoon revealed that something more than minor recalibrations would
be needed. Because of the car’s layout, the exhaust system of the rear engine is
longer than that of the front and, since the air pressure is some 15 per cent
lower at Bonneville than Wittering, the front engine turbo was boosting two to
three seconds before the rear. With the front engine doing all the work and with
no load on the rear engine, its turbos simply refused to come onto boost at all.
Saturday August 12th, the first day of Speed Week,
yielded a peak speed of only 163 mph before the team ran out of time on the
salt. Sunday was even more frustrating when, after a three-hour wait to get a
run, they were still unable to solve the boost problem. On Monday 14th they
achieved 226 mph on the salt but still could not encourage the rear engine to
boost. “226mph was not bad,” says Beasley, “considering the front engine was
doing all the work.” To overcome this situation he decided to reduce the
fuelling of the front engine in first gear, giving the rear engine a chance to
catch up. But when they returned to the salt on Tuesday, the problem reversed
and the front engine failed to boost.
Balance Pipe Solves Boost Problem
In order to resolve this issue once and for all,
Beasley and his team decided to fit a balance pipe between the induction
manifolds of the two engines to equalise the pressure on the air side of the
turbos. They worked through the night on this solution but in parallel, they
also developed a novel run strategy which mirrored the way in which the
JCB444-LSR engines were tested at Ricardo – initially applying load at low speed
to raise the exhaust temperature before allowing the engine to go onto boost.
While this is done in the test cell through applying load through the
dynamometer, the same could be achieved by applying the brake under power during
the early stages of a record run.
Wednesday morning dawned and the modified
Dieselmax made six runs at Wendover airport with driver Andy Green using the new
‘left foot brake’ technique to raise the exhaust temperatures to over 400
degrees Centigrade. It was one of those Eureka moments as both engines came
cleanly onto boost for the first time since the car had been run at Wittering:
the machine accelerated as never before. Maddeningly, though, strong cross winds
prevented a run on the salt that afternoon. By Thursday afternoon, however, with
good salt conditions and all engine and vehicle development issues resolved, the
Dieselmax performed exactly as intended, achieving a measured mile speed of 308
mph.
On Friday, in the cool of the early morning, they
returned to make the second run and Andy Green comfortably averaged 325 mph,
setting a new Bonneville record of 317.021 mph. The Dieselmax had become the
fastest ever diesel to run at Bonneville but, unbeknown to outsiders, Green had
missed the mile marker and hit 350 mph beyond the measured mile. “The car was
developing just over 1000 bhp from itstwo engines at the time, was not
yet at full boost and still in fifth gear not sixth, so everyone gained
confidence for the world record attempt,” says Beasley.
The World Record Beckons
Now for the big one: the official FIA land speed
record for diesel cars. With Speed Week over, the team returned to Wendover in
order to fit the 750 bhp engines for the attempt. “There was some pressure to
leave well alone, to leave the existing engines in place now we had them sorted,
but I knew they had done their allotted work,” recalls Beasley. Yet when running
the new engines for the first time on the Monday morning, a fuel pump oil seal
failed, causing further delays. At dusk there was just time for a few test runs
on the airfield runway.
Returning to the salt on Tuesday, they prepared
for the first record run and the car was ready on the start line before dawn.
Green left the line, pushed by the JCB Fastrac as usual, on what looked like a
promising start. Then, just 1.5 miles into the first run, disaster struck and
the Dieselmax coasted to a halt, Green reporting a ‘total power failure’ over
the radio. As it turned out, a chafed wire beneath the dashboard had killed the
electrical systems. With the fault repaired, they tried again. The first run
average was 324.265 mph, despite the engines overheating and the power being
automatically reduced by a fifth. On the return run, made with just 11 minutes
to spare before the one hour cut-off, Green averaged 333.364 mph, giving a
two-way average of 328.767 mph and setting a new international record in the
process.
The team was ecstatic. “Andy ran to the 330 mph
target but the speed climbed to 345 mph. He backed off, but inadvertently hit
the exhaust brake when he did so, decelerating the car by some 20 mph,” says
Beasley. It was a fantastic result but the decision was taken to return the
following day and attempt to raise the bar still higher.
The team duly returned again on Wednesday, still
weary following a late night spent modifying the cooling circuit on the front
engine. At 7.39am Green pointed the streamliner’s long nose towards Bonneville’s
famous Floating Mountain and began his run. This time the strategy for dealing
with the turbo lag worked a little too well and Green averaged a staggering
365.779 mph using only 1250 bhp and still only in fifth gear. “This time the
turnaround was really slick,” recalls Beasley. “We got the pre-heaters on
because the cooling mods had worked better than planned - but even so, the front
engine was too cool and it took Andy a mile to get it on boost on the return
run.”
“Andy decided to stick with it, slowing the car
then bringing it back onto the target temperature on the brakes. When he
released the brakes the car just flew and we got our 335.695 mph run,” crowed
Beasley. Despite his annoyance at the interrupted second run, Green had raised
the record to 350.092 mph, exactly what the team had set out to achieve. “But
the car had not used sixth gear, full power or even maximum revs. It was pulling
3700 rpm, developing 1250 bhp and was still accelerating,” says Beasley. “This
car has the potential to go a lot faster and our calculations show that it could
achieve almost 400 mph at full power if it was fitted with the appropriate tyres
– but that is, of course, a call that can only be made by JCB.”
Most importantly, the team not only succeeded in
all its objectives but also did so within what was an unprecedentedly demanding
timescale, even by the standards of motorsport. As Penny sums up: “This
initiative has served to demonstrate the ultimate performance that can be
achieved from a diesel engine and at the same time the very robust architecture
of the production JCB444 engine from which the JCB444-LSR has been developed by
Ricardo. This has been an exceptionally demanding program for us but the team
has delivered the engine and vehicle to time and to the required performance
under very challenging circumstances.”
“Most critically of all, though,” stresses Penny,
“Dieselmax demonstrates many of the advanced engineering technologies which
Ricardo is developing in order to make the vehicles of tomorrow more energy
efficient and less polluting.”
Dr
Tim Leverton, JCB engineering director
“The
outcome of this project has a significant influence on the application of diesel
engines and our own range in particular. The increase in power means the break
point at which a six-cylinder engine becomes necessary has risen – and this
clearly has major commercial implications. The compact power unit gives us more
scope in terms of the type of vehicles we can design.
“We
could not have completed this project without Ricardo. We do not have the tools,
the people or the know-how. This project was really an extension of the working
relationship we already had with Ricardo following the development of the
production 444 engine. To succeed in this kind of venture you simply need enough
hours and the right guys; Ricardo has the right guys and they are a highly
motivated and dedicated team. I didn’t expect to achieve this in a one year
program.”
Wing
Commander Andy Green, driver
“It
was a classic record car experience but the diesel engine made it unique.
Sluggish at slow speed, when it suddenly came onto boost the car would just take
off. The left foot brake technique we developed to overcome the boost problem at
high altitudes produced far better acceleration than we experienced, even during
the UK tests. In the end, the car ended up being so fast at the top end that it
outstripped all expectations.
“Although
Matt Beasley and his team are used to working in a more controlled environment,
they reacted to the pressures of a land speed record attempt superbly well and
evolved into a true, land speed record engineering team. In Matt Beasley I had
my ‘man of the match’ and thereafter he became known as ‘Max Diesel.’ He showed
great leadership and engineering development work under intense team, company
and media pressure, and indeed the scrutiny of an international audience.”
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